import numpy as np
import sys
import random
import pygame
import flappy_bird_utils
import pygame.surfarray as surfarray
from pygame.locals import *
from itertools import cycle

FPS = 30
SCREENWIDTH  = 288
SCREENHEIGHT = 512

pygame.init()
FPSCLOCK = pygame.time.Clock()
SCREEN = pygame.display.set_mode((SCREENWIDTH, SCREENHEIGHT))
pygame.display.set_caption('Flappy Bird')

IMAGES, SOUNDS, HITMASKS = flappy_bird_utils.load()
PIPEGAPSIZE = 100  # gap between upper and lower part of pipe
BASEY = SCREENHEIGHT * 0.79

PLAYER_WIDTH = IMAGES['player'][0].get_width()
PLAYER_HEIGHT = IMAGES['player'][0].get_height()
PIPE_WIDTH = IMAGES['pipe'][0].get_width()
PIPE_HEIGHT = IMAGES['pipe'][0].get_height()
BACKGROUND_WIDTH = IMAGES['background'].get_width()

PLAYER_INDEX_GEN = cycle([0, 1, 2, 1])


class GameState:
	def __init__(self):
		self.score = self.playerIndex = self.loopIter = 0
		self.playerx = int(SCREENWIDTH * 0.2)
		self.playery = int((SCREENHEIGHT - PLAYER_HEIGHT) / 2)
		self.basex = 0
		self.baseShift = IMAGES['base'].get_width() - BACKGROUND_WIDTH

		np.random.seed(2)
		self.pipeArray = np.random.randint(0, 7, 10000)
		self.t = 0

		newPipe1 = getRandomPipe(self.pipeArray[0])
		newPipe2 = getRandomPipe(self.pipeArray[1])
		self.upperPipes = [
			{'x': SCREENWIDTH, 'y': newPipe1[0]['y']},
			{'x': SCREENWIDTH + (SCREENWIDTH / 2), 'y': newPipe2[0]['y']},
		]
		self.lowerPipes = [
			{'x': SCREENWIDTH, 'y': newPipe1[1]['y']},
			{'x': SCREENWIDTH + (SCREENWIDTH / 2), 'y': newPipe2[1]['y']},
		]

		# player velocity, max velocity, downward accleration, accleration on flap
		self.pipeVelX = -4
		self.playerVelY    =  0    # player's velocity along Y, default same as playerFlapped
		self.playerMaxVelY =  10   # max vel along Y, max descend speed
		self.playerMinVelY =  -8   # min vel along Y, max ascend speed
		self.playerAccY    =   1   # players downward accleration
		self.playerFlapAcc =  -9   # players speed on flapping
		self.playerFlapped = False # True when player flaps

	def frame_step(self, input_actions):
		pygame.event.pump()
		reward = 0.1
		terminal = False

		if sum(input_actions) != 1:
			raise ValueError('Multiple input actions!')

		# input_actions[0] == 1: do nothing
		# input_actions[1] == 1: flap the bird
		# the original version of python flappy bird allows the bird go out of the top of the screen a little,
		# but the version of DQN flappy bird makes the bird stay inside the screen(see the condition statement in line 100.)
		if input_actions[1] == 1:
			if self.playery > -2 * PLAYER_HEIGHT:
				self.playerVelY = self.playerFlapAcc					# if the bird stay inside the capable range then it can flap
				self.playerFlapped = True
				#SOUNDS['wing'].play()

		# check for score (if the bird passes the pipe, we get one point)
		playerMidPos = self.playerx + PLAYER_WIDTH / 2
		for pipe in self.upperPipes:
			pipeMidPos = pipe['x'] + PIPE_WIDTH / 2
			if pipeMidPos <= playerMidPos < pipeMidPos + 4:
				self.score += 1
				#SOUNDS['point'].play()
				reward = 1

		# playerIndex basex change
		if (self.loopIter + 1) % 3 == 0:
			self.playerIndex = next(PLAYER_INDEX_GEN)
		self.loopIter = (self.loopIter + 1) % 30                        # make sure loopIter will not inscrease infinitely
		self.basex = -((-self.basex + 100) % self.baseShift)            # makes the base looks like moving backward

		# player's movement
		if self.playerVelY < self.playerMaxVelY and not self.playerFlapped:				# if flapped, keep upward trend (line 73)
			self.playerVelY += self.playerAccY											# trend of downward
		if self.playerFlapped:
			self.playerFlapped = False
		self.playery += min(self.playerVelY, BASEY - self.playery - PLAYER_HEIGHT)		# I don't know the meaning of the second argument
		if self.playery < 0:															# keep the bird staying in the screen
			self.playery = 0

		# move pipes to left
		for uPipe, lPipe in zip(self.upperPipes, self.lowerPipes):
			uPipe['x'] += self.pipeVelX
			lPipe['x'] += self.pipeVelX

		# add new pipe when first pipe is about to touch left of screen
		if 0 < self.upperPipes[0]['x'] < 5:
			newPipe = getRandomPipe(self.pipeArray[self.t])
			self.t += 1
			if self.t >= 10000:
				self.t = 0
			self.upperPipes.append(newPipe[0])
			self.lowerPipes.append(newPipe[1])

		# remove first pipe if its out of the screen
		if self.upperPipes[0]['x'] < -PIPE_WIDTH:
			self.upperPipes.pop(0)
			self.lowerPipes.pop(0)

		# check if crash here
		isCrash= checkCrash({'x': self.playerx, 'y': self.playery,
							 'index': self.playerIndex},
							self.upperPipes, self.lowerPipes)
		if isCrash:
			#SOUNDS['hit'].play()
			#SOUNDS['die'].play()
			terminal = True
			self.__init__()
			reward = -1

		# draw sprites
		SCREEN.blit(IMAGES['background'], (0,0))

		for uPipe, lPipe in zip(self.upperPipes, self.lowerPipes):
			SCREEN.blit(IMAGES['pipe'][0], (uPipe['x'], uPipe['y']))
			SCREEN.blit(IMAGES['pipe'][1], (lPipe['x'], lPipe['y']))

		SCREEN.blit(IMAGES['base'], (self.basex, BASEY))
		# print score so player overlaps the score
		# showScore(self.score)
		SCREEN.blit(IMAGES['player'][self.playerIndex],
					(self.playerx, self.playery))

		image_data = pygame.surfarray.array3d(pygame.display.get_surface())
		pygame.display.update()
		# FPSCLOCK.tick(FPS)
		#print self.upperPipes[0]['y'] + PIPE_HEIGHT - int(BASEY * 0.2)
		return image_data, reward, terminal


def getRandomPipe(index):
	"""returns a randomly generated pipe"""
	# y of gap between upper and lower pipe
	gapYs = [20, 30, 40, 50, 60, 70, 80, 90]
	gapY = gapYs[index]

	gapY += int(BASEY * 0.2)
	pipeX = SCREENWIDTH + 10

	return [
		{'x': pipeX, 'y': gapY - PIPE_HEIGHT},  # upper pipe
		{'x': pipeX, 'y': gapY + PIPEGAPSIZE},  # lower pipe
	]


def showScore(score):
	"""displays score in center of screen"""
	scoreDigits = [int(x) for x in list(str(score))]
	totalWidth = 0 # total width of all numbers to be printed

	for digit in scoreDigits:
		totalWidth += IMAGES['numbers'][digit].get_width()

	Xoffset = (SCREENWIDTH - totalWidth) / 2

	for digit in scoreDigits:
		SCREEN.blit(IMAGES['numbers'][digit], (Xoffset, SCREENHEIGHT * 0.1))
		Xoffset += IMAGES['numbers'][digit].get_width()


def checkCrash(player, upperPipes, lowerPipes):
	"""returns True if player collders with base or pipes."""
	pi = player['index']
	player['w'] = IMAGES['player'][0].get_width()
	player['h'] = IMAGES['player'][0].get_height()

	# if player crashes into ground
	if player['y'] + player['h'] >= BASEY - 1:
		return True
	else:

		playerRect = pygame.Rect(player['x'], player['y'],
					  player['w'], player['h'])

		for uPipe, lPipe in zip(upperPipes, lowerPipes):
			# upper and lower pipe rects
			uPipeRect = pygame.Rect(uPipe['x'], uPipe['y'], PIPE_WIDTH, PIPE_HEIGHT)
			lPipeRect = pygame.Rect(lPipe['x'], lPipe['y'], PIPE_WIDTH, PIPE_HEIGHT)

			# player and upper/lower pipe hitmasks
			pHitMask = HITMASKS['player'][pi]
			uHitmask = HITMASKS['pipe'][0]
			lHitmask = HITMASKS['pipe'][1]

			# if bird collided with upipe or lpipe
			uCollide = pixelCollision(playerRect, uPipeRect, pHitMask, uHitmask)
			lCollide = pixelCollision(playerRect, lPipeRect, pHitMask, lHitmask)

			if uCollide or lCollide:
				return True

	return False


def pixelCollision(rect1, rect2, hitmask1, hitmask2):
	"""Checks if two objects collide and not just their rects"""
	rect = rect1.clip(rect2)

	if rect.width == 0 or rect.height == 0:
		return False

	x1, y1 = rect.x - rect1.x, rect.y - rect1.y
	x2, y2 = rect.x - rect2.x, rect.y - rect2.y

	for x in range(rect.width):
		for y in range(rect.height):
			if hitmask1[x1+x][y1+y] and hitmask2[x2+x][y2+y]:
				return True
	return False

